Caption: First sample of prehistoric water from a sub-glacial Antarctic lake. This sample is from Lake Vostok, on the east of the continent. The water was obtained by Russian scientists who drilled through nearly four kilometres of ice to reach the lake. The lake covers 15,000 square kilometres and is thought to be completely cut off from any of the other sub-glacial lakes. The water sample is thought to be over a million years old and could contain microorganisms unknown to science.